Just the fact you have to pay for something that is free.

Software Chrome App
1

Subject says it all

2

Paying the salaries of highly skilled developers to make and support an app certainly isn't free.

If you don't want to pay for the app, you can see if you can get the standard Arduino IDE running on your Chrome computer:
Instructions here: Desktop IDE running on Chromebook via chroot - Interfacing w/ Software on the Computer - Arduino Forum
As an alternative to that approch, there is also an arduino_ide chromebrew package.

3

Note that the Arduino IDE also has been developed at some expense. If you are open-source, then you should allow contributors as for the IDE. Open source makes sense. Charging for a particular platform is not consistent with the open-source philosophy.

And, I might add, the posting throttle of once every five minutes makes it hard to achieve the 100 post limit. Who thought this was a good idea? And why?

Joseph M. Newcomer, PhD (ret)